Choroidal thickness in young myopic adults assessed by enhanced depth imaging optical coherence tomography

Purpose To compare choroidal thickness of emetropic eyes and ones with different degree of myopia in young adults. Methods 40 participants (80 eyes) had choroidal measurements using enhanced depth imaging spectral domain optical coherence tomography at three locations: fovea, 3mm nasally and 3mm temporally to it. According to their refractive error patients were divided into 3 groups: emetropia (from +0.5 D to -0.5 D)- 22 eyes, mild to moderate degree myopia (from -1.0 D to -6.0 D) - 34 eyes, high degree myopia (-6.0 D & greater) - 24 eyes. Axial length biometry and autorefractometry were also performed. Results The mean age of the participants was 23.6 years (standard deviation ± 1.5). The average choroidal thickness at fovea, 3mm nasally and 3mm temporally was estimated to be 352.5 (median 328.0, interquartile range 116.5) µm, 161.0 (139.0, 88.5) µm and 311.6, (298.5, 101.5) µm respectively. Subfoveal and temporal choroid was significantly thinner in high degree myopic eyes than in the group of low to moderate myopia and emetropic eyes (p < 0.05). At the fovea the choroid was thicker than nasally and temporally to it (p<0.05). A moderate negative correlation was found between the thickness of the choroid and the degree of myopia (ρ= -0.44; p < 0.01). Axial length was significantly shorter in normal vision group than in the groups of myopia (p < 0.05) and correlated negatively with the central choroidal thickness (ρ= -0.47; p < 0.01). Conclusion Myopic young adults had significantly thinner central choroid layer compared to emetropic individuals. At all measured locations the choroidal thickness decreased with the higher degree of myopia and longer axial length.